Effect of halofuginone lactate on the occurrence of Cryptosporidium parvum and growth of neonatal dairy calves

Thirty-one Holstein bull calves were purchased at birth from 3 dairy farms in Eastern Ontario. Each calf was assigned at random to oral treatment with either 5 mg of halofuginone lactate in 10.0 mL of aqueous carrier solution (Halocur, base comprised 10 mg of benzoic acid, 100 mg of lactic acid, and 0.3 mg of tartrazine) or 10 mL of placebo (Halocur base minus the active ingredient, halofuginone lactate) administered 15 to 30 min after morning milk feeding for the first 7 d of life. Intakes of milk, calf starter, and water, and fecal consistency score were recorded daily for 56 d. Calf weights were recorded weekly for 56 d. Fecal samples were taken from all calves at approximately 2, 7, 14, 21, and 28 d of age for isolation of Cryptosporidium parvum oocysts. Logistic and linear regression analyses were used to assess the effect of treatment on the incidence of diarrhea and C. parvum infection status. The odds of C. parvum shedding among calves in the halofuginone lactate-treated group was 70% lower than the odds of shedding among calves in the placebo group. In calves treated with halofuginone lactate, no oocyst shedding occurred until 2 wk of age, whereas 12.5% of calves in the placebo group began shedding oocysts during wk 1. From all ages of placebo-treated calves, 31 of 73 samples (42.5%) were positive for C. parvum, whereas only 15 of 67 samples (22.4%) from all ages of halofuginone lactate-treated calves tested positive. The largest number of C. parvum-positive samples occurred in the third week of life. There was a significant delay of 3.1 d in the incidence of diarrhea among calves treated with halofuginone lactate. Intake of milk and starter, body weight gains, and age at weaning were not significantly different between treatment groups.     

Inhibitory effect of organic acid salts on spoilage flora in culture medium and cured cooked meat products under commercial manufacturing conditions

Lactobacillus curvatus, isolated from a spoiled vacuum-packaged 'pariza' type meat product, was used to inoculate modified MRS broth containing sodium lactate, sodium acetate and potassium sorbate in different concentrations, alone or in inter se combinations. Two commercial preparations (MIX 1 and MIX 2) were also used containing combinations of the above antimicrobials. Results from the preservatives addition to the culture medium showed highest antimicrobial activity in the case of the sodium lactate (2%, 3% or 4%), sodium acetate (0.5%) and potassium sorbate (0.15%) combination. Results from the preservatives addition to two types of thermally processed meats showed that sodium lactate and the combination of sodium lactate, sodium acetate and potassium sorbate were the most effective; extending the products shelf life an additional 10 days. Finally, MIX 1 and MIX 2 suppressed the lactic acid bacteria (LAB) growth in the culture medium but not in the final product.     

彼阳新盖口服液中乳酸钙和葡萄糖酸锌含量测定

本文研究乳酸钙、葡萄糖酸锌含量的测定。以(2-吡啶偶氮)-2-萘酚(PAN)为指示剂,乙二胺四乙酸二钠为滴定剂,通过控制溶液酸度分别测定彼阳新盖口服液中乳酸钙和微量葡萄糖酸锌的含量;同时还应用meso-四-(4-(4-甲基,3-磺基苯)卟啉分光光度法直接测定口服液中微量的葡萄糖酸锌,结果准确。     

十二水合硫酸铁铵催化合成乳酸正丁酯

将十二水合硫酸铁铵作催化剂,应用于乳酸和正丁醇的酯化反应中,合成了乳酸正丁酯。例如,将０．１ｍｏｌ乳酸、０．２ｍｏｌ正丁醇和０．００３ｍｏｌ催化剂加热回流分水２ｈ,制得乳酸正丁酯,产品收率达９９％。     

电性距离矢量和神经网络用于三唑并嘧啶磺酰胺类除草剂的QSAR研究

为了研究三唑并嘧啶磺酰胺类除草剂对乙酰乳酸合成酶(aceto lactate synthase,ALS)抑制活性(pI50)的定量构效关系,以电性距离矢量(Mk)表征了31种三唑并嘧啶磺酰胺类化合物的分子结构;利用最佳变量子集回归的方法建立了含有6个参数(M2、M10、M14、M15、M67、M85)的QSAR模型.该模型的相关系数R及交叉验证相关系数RCV分别为0.911、0.887,具有良好的稳健性和预测能力;以此6个参数为人工神经网络输入层,设定6∶3∶1的网络结构,构建人工神经网络的BP算法模型,相关系数R提升为0.988.结果表明:影响三唑并吡啶磺胺类除草剂抑制活性pI50的主要因素是-CH3、-CH2-、>C-、-O-、>N-及-X(-F,-Cl)等分子结构单元,且pI50与M2、M10、M14、M15、M67、M85呈现良好的非线性关系,为设计高活性的ALS抑制剂提供理论依据.     

DMAP催化合成O-乙酰基乳酸酯

以 4 (二甲氨基 )吡啶 ( DMAP)为催化剂 ,合成了 O 乙酰基乳酸乙酯、O 乙酰基乳酸丁酯。对影响反应的诸因素进行了讨论 ,O 乙酰乳酸酯的收率达 80 %以上     

The relation between cycling time to exhaustion and anaerobic threshold

Abstract

This study investigated whether the anaerobic threshold (AnT) could be used to predict prolonged work capacity measured as cycling time to exhaustion (= endurance time) and which factors, in addition to relative exercise intensity, could explain variation in endurance time. Theoretical exercise intensities corresponding to certain endurance times were also calculated. The hyperbolic and exponential functions between cycling time and relative work rate (WR[%]), as well as between cyling time and relative oxygen uptake ([Vdot]O₂[%]) were fitted to the pooled data (n = 45) of 17 subjects. The WR(%) and [Vdot]O₂ (%) were expressed as a percentage of the subject's own AnT- and maximum -values. At WR corresponding to AnT (i.e., 70% of WR_max) an average subject could cycle 60 min according to both AnT- or maximum-related exponential function. When prediction was done for an endurance time of 4 h, the AnT-related exponential function gave 2·9%-units ( = 11 W or ～0·15 O₂1 · min^?1) lower intensity level (51% of WR_max than the maximum-related function (54% of WR_max). The WR(%) alone explained 54% and 70% of the variation in endurance time of the AnT-related and maximum-related exponential functions, respectively. Muscle fibre composition and initial blood lactate or relative muscle glycogen depletion (change in muscle glycogen as percentage) increased significantly the explanatory power of these models. The differences between the observed and expected exercise times correlated with blood lactate accumulation (r = ?0·42; p < 0·01), muscle fibre composition (r = 0·33; p < 0·05) and relative muscle glycogen depletion (r = 0·67; p < 0·01). It was concluded that the capacity for prolonged work measured as cycling time to exhaustion can be estimated by AnT-related power output, and that the exponential function model is the most suitable. Prediction power of the model can be improved by multiple regressions including muscle fibre composition, initial blood lactate level and relative muscle glycogen depletion.     

阳离子交换树脂催化合成乳酸异戊酯的研究

以阳离子交换树脂为催化剂，研究了乳酸与异戊醇合成乳酸异戊酯的反应条件，结果表明：用1.0g阳离子交换树脂作催化剂、0.1mol（9g）乳酸，当乳酸与异戊醇的摩尔比为1:2，在回流条件下反应3h后，酯产率可达87.5%，本方法具有催化活性较高，对设备无腐蚀、三废排放少，催化剂可重复使用多次等特点。     

维生素C乳酸酯酶催化合成的响应曲面分析

以脂肪酶Novozym 435催化维生素C和乳酸乙酯转酯合成维生素C乳酸酯。采用基于四因素五水平的中心组合设计实验的响应曲面法,分析了温度(30~70℃)、酶量(10~30 mg)、维生素C质量浓度(9.36~28.07g/L)和反应时间(24~72 h)以及它们的交互作用对维生素C乳酸酯产率的影响。获得的最佳实验条件为:温度50℃,维生素C的质量浓度18.71 g/L,脂肪酶质量20 mg和反应时间48 h。在最佳条件下,维生素C乳酸酯的预计产率为71.20%,与实际产率71.12%符合较好。     

纳米TiO_2催化合成乳酸丁酯

以乳酸、正丁醇为原料,纳米TiO2为催化剂,合成了乳酸丁酯。确定了最佳合成工艺条件为:催化剂用量1.0g;酸醇物质的量之比1∶1.4;带水剂甲苯10mL;反应时间3.0h;酯化率达94.7%。采用固体纳米粒子催化,工艺简单、催化剂用量少、时间短、无三废。